Practical 3D Printing: Common Issues & Troubleshooting

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Common Issues & Troubleshooting

06.49

00:00	One of the big advantages of SLA over FDM is its relatively trouble-free nature but that doesn't mean it's not without its potential headaches.
00:08	This module won't be an exhaustive list of all the problems that we might encounter as they were covered in detail in the FDM section but more the key ones specific to the SLA process that are worth discussing and more importantly how we should go about addressing them.
00:25	It's important to properly understand all the common problems discussed in this module but we'll save you the trouble of remembering each one as we've prepared a troubleshooting cheat sheet that you can easily refer back to.
00:38	You'll find a link to this underneath this module.
00:41	Let's start by covering print failures which is typically the result of the print coming off the build plate while printing.
00:48	The first thing we need to check is that the machine is set up properly and everything is in good working order.
00:54	For printers that don't solely rely on auto-leveling we can re-level the build plate.
00:59	We can also check if the build plate is in good condition.
01:03	Placing a straight edge over the build plate in multiple directions can help us determine if it is warped and is no longer flat.
01:11	Likewise, the release film could be damaged.
01:13	This is a wear item so after a while it will need to be replaced.
01:17	If the film looks stretched, scratched or overly cloudy this can indicate that it's on its way out.
01:23	The LCD screen is also a wear item that will need to be replaced at some point.
01:28	As pixels stop working we can start to see issues in the masking and we'll end up with areas of the resin being exposed that shouldn't be and vice versa.
01:37	Basically, this will result in holes in the model or stalactite structures hanging from the build plate.
01:44	While the LCD screen shouldn't need to be replaced as often as the release film, the service life of both of these components is going to depend on the nature of the prints and how often we use the printer.
01:55	For example printing up much longer exposure times introduces a lot of extra heat to the LCD shortening its life.
02:04	After we're happy with the working order and the setup of the printer, the next thing to consider is the print settings.
02:10	If our prints are pulling off the build plate then it's clear that the release force or the weight of the part is overcoming the adhesion between the part and the build plate.
02:19	So, we either need to decrease the release force or increase the build plate adhesion.
02:25	In terms of settings we first need to consider the bottom layers.
02:28	In chitterbox for example these can be accessed through the slice settings tab.
02:33	For most prints we should have around 5 bottom layers and these will be significantly overexposed at around 30 seconds or so to promote adhesion.
02:43	Increasing these values slightly can help with adhesion but having them too far from the resin supplier's recommendations should be a red flag that something else is wrong.
02:54	Certain orientations and part geometries could result in a small footprint or foundation on the build plate for a relatively large and heavy part.
03:03	In this case we might want to add a raft under the part and any supports.
03:07	The raft essentially forms a wider foundation and contact area for the part on the build plate.
03:13	It can be set up under the support settings in our slicer.
03:17	Looking at chitterbox again we can change the raft shape under the basic settings and see the difference in our workspace.
03:24	Alternatively under the advanced settings we can also increase the area and the thickness.
03:29	The release force is also a function of the geometry of the part with larger cross sectional areas resulting in higher release forces.
03:38	Large flat sections parallel to the release film should be avoided when determining the print orientation.
03:45	Any geometry that will cause a large suction cup will also cause a similar issue.
03:50	If these can't be avoided then consider adding a hole for relief of this vacuum.
03:56	Past this decreasing the lift speed is a simple way of directly lowering the release force with a small increase in print time.
04:04	Let's move on from print failures to the topic of surface quality or more specifically issues with the surface appearance of the part.
04:11	Although these could translate to functional issues for some applications as well.
04:16	The first thing to discuss is witness marks from supports.
04:20	Changing print orientations and support settings goes a long way here and can significantly reduce these marks.
04:27	For example we could change the print orientation to minimize the amount of supports required or move them into a different face.
04:34	Or we could reduce the size of the support tips to make the marks even smaller.
04:39	However, in many cases support marks are going to be inevitable and might need to be addressed with post processes.
04:46	As a more general approach to overall surface finish we need to ensure proper calibration of our print settings and that will likely involve experimentation with exposure times and possibly using some form of calibration print like the XP2 validation matrix that we covered previously.
05:03	Most modern printers are capable of printing with multiple settings in different zones at one time to speed this process up.
05:11	Similar to surface quality issues are dimensional inaccuracies and these tend to go hand in hand.
05:16	Where if our surface finish is unsatisfactory due to poor calibration this will often translate into dimensional inaccuracies.
05:24	As we discussed in the earlier calibration module there can be a disconnect between the slicer and the printer.
05:30	Essentially the slicer thinks the LCD is a different size to what it really is.
05:35	To fix this we can tweak the printer settings for the screen size in the slicer, but like always we should avoid using this as a bandaid to cover up deeper issues as we'll still find inconsistencies regardless.
05:48	As a final point before wrapping up understand it's important to get your head around the causes of issues so we don't go chasing other fixes that could bandaid the problem but come with other compromises.
06:00	Okay let's summarize what we've covered.
06:02	SLA 3D printing tends to be relatively trouble-free in its nature although it is relatively laborious especially around cleaning.
06:11	If we're running into print failures we first need to consider the setup of the printer and ensure everything is in good work order.
06:34	This hasn't been an exhaustive list, and we've discussed other issues and best practices throughout the other modules of this course, so check back to the relevant modules for a more in-depth refresher.